Absolute surface coverage measurement demonstrated using vibrational overtones.Using evanescent-wave cavity ring-down spectroscopy (EW-CRDS), a technique pioneered at NIST, measurement of absolute surface coverage with submonolayer sensitivity has been demonstrated. The first C-H stretching overtones of trichloroethylene (TCE TCE
TCE Environment A volatile chlorinated hydrocarbon that boils at 88ºC and is highly soluble–1000 ppm in water, with various industrial uses Toxicity Peripheral neuropathy, carcinogenic. ), cis-dichloroethylene, and trans-dichloroethylene were probed for the gas- and adsorbed-phase species using a seeded optical parametric amplifier An optical parametric amplifier, abbreviated OPA, is a laser light source that emits light of variable wavelengths by an optical parametric amplification process. Optical parametric generation (OPG)
This light emission is based on the nonlinear optical principle. . Polarized A one-way direction of a signal or the molecules within a material pointing in one direction. absolute adsorbate ad·sor·bate
An adsorbed substance.
Noun 1. adsorbate - a material that has been or is capable of being adsorbed spectra were obtained by EW-CRDS using a high-finesse fused-silica monolithic optical resonator, while absolute absorption cross sections for the gasphase species were determined by conventional CRDS. A measure of the average transition moment orientation on the surface, which is required for monolayer coverage determination, was derived from the polarization anisotropy of the surface spectra. As the vector-character of absorption yields only an average tilt angle to characterize the orientation distribution, the method is accurate for highly oriented, unimodal Adj. 1. unimodal - having a single mode
statistics - a branch of applied mathematics concerned with the collection and interpretation of quantitative data and the use of probability theory to estimate population parameters surface distributions. For such well-ordered systems, coverage uncertainties of [+ or -]0.1 monolayer are possible. The EW-CRDS technique also was shown to provide a significant advance in sensitivity for chemical detection of TCE, which is a major environmental contaminant.
This work, performed collaboratively by NIST and the Eindhoven University of Technology The Eindhoven University of Technology (in Dutch: Technische Universiteit Eindhoven or TU/e, and formerly Technische Hogeschool Eindhoven or THE) is a university of technology located in Eindhoven, the Netherlands. in the Netherlands, has been supported by the Environmental Management Science Program of the Department of Energy.
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